<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<html>
<head>
<!-- Copyright 1997 The Open Group, All Rights Reserved -->
<title>pow</title>
</head><body bgcolor=white>
<center>
<font size=2>
The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

</font></center><hr size=2 noshade>
<h4><a name = "tag_000_007_1006">&nbsp;</a>NAME</h4><blockquote>
pow - power function
</blockquote><h4><a name = "tag_000_007_1007">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

#include &lt;<a href="math.h.html">math.h</a>&gt;

double pow(double <i>x</i>, double <i>y</i>);
</code>
</pre>
</blockquote><h4><a name = "tag_000_007_1008">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>pow()</i>
function computes the value of
<i>x</i>
raised to the power
<i>y,</i>
<i>x<sup><small>y</small></sup></i>.
If
<i>x</i>
is negative,
<i>y</i>
must be an integer value.
<p>
An application wishing to check for error situations should set
<i>errno</i>
to 0 before calling
<i>pow()</i>.
If
<i>errno</i>
is non-zero on return,
or the return value is NaN,
an error has occurred.
</blockquote><h4><a name = "tag_000_007_1009">&nbsp;</a>RETURN VALUE</h4><blockquote>
Upon successful completion,
<i>pow()</i>
returns the value of
<i>x</i>
raised to the power
<i>y.</i>
<p>
If
<i>x</i>
is 0 and
<i>y</i>
is 0, 1.0 is returned.
<p>
If
<i>y</i>
is NaN, or
<i>y</i>
is non-zero and
<i>x</i>
is NaN, NaN is returned and
<i>errno</i>
may be set to [EDOM].  If
<i>y</i>
is 0.0 and
<i>x</i>
is NaN, either 1.0 is returned, or NaN is returned and
<i>errno</i>
may be set to [EDOM].
<p>
If
<i>x</i>
is 0.0 and
<i>y</i>
is negative, -HUGE_VAL
is returned and
<i>errno</i>
may be set to [EDOM]
&nbsp;or [ERANGE].
<p>
If the correct value would cause overflow, &plusmn;HUGE_VAL is returned, and
<i>errno</i>
is set to [ERANGE].
<p>
If the correct value would cause underflow, 0 is returned and
<i>errno</i>
may be set to [ERANGE].
</blockquote><h4><a name = "tag_000_007_1010">&nbsp;</a>ERRORS</h4><blockquote>
The
<i>pow()</i>
function will fail if:
<dl compact>

<dt>[EDOM]<dd>
The value of
<i>x</i>
is negative and
<i>y</i>
is non-integral.

<dt>[ERANGE]<dd>
The value to be returned would have caused overflow.

</dl>
<p>
The
<i>pow()</i>
function may fail if:
<dl compact>

<dt>[EDOM]<dd>
The value of
<i>x</i>
is 0.0 and
<i>y</i>
is negative,
&nbsp;or
<i>y</i>
is NaN.

<dt>[ERANGE]<dd>
The correct value would cause underflow.

</dl>
<p>
No other errors will occur.
</blockquote><h4><a name = "tag_000_007_1011">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_007_1012">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_007_1013">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_007_1014">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="exp.html">exp()</a></i>,
<i><a href="isnan.html">isnan()</a></i>,
<i><a href="math.h.html">&lt;math.h&gt;</a></i>.
</blockquote><h4>DERIVATION</h4><blockquote>
Derived from Issue 1 of the SVID.
</blockquote><hr size=2 noshade>
<center><font size=2>
UNIX &reg; is a registered Trademark of The Open Group.<br>
Copyright &copy; 1997 The Open Group
<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]

</font></center><hr size=2 noshade>
</body></html>

